When PC Gwen Cooper sees an investigation team from Torchwood resurrect a murdered man and ask him questions about his death, she get curious.  She follows up on the only name she overheared: "Captain Jack Harkness".  She finally gets into the Torchwood labs under the Millenium Fountain in Cardiff.  Jack explains Torchwood to Gwen - how they operate outside the law and the UN to better understand alien technology in order to help the Earth.  Jack also tells her that he's slipped her an amnesia drug so she won't remember their meeting.  After she awakens and goes back to work, she sees a picture of a murder weapon and it triggers some of her memories.  She heads back to the Millenium Fountain, unsure of what she'll find.